China will limit exports of refined petroleum products to North Korea starting October 1, its commerce ministry said, confirming Beijing's participation in new UN sanctions intended to rein in its rogue neighbour.

The United Nations Security Council, including permanent member Beijing, approved tough sanctions against Pyongyang last week in response to its sixth and most powerful nuclear test.

Washington had initially sought a full oil embargo, but softened its stance to secure backing from Russia and China -- the North's sole ally and main trading partner, responsible for around 90 percent of its commerce.

In a statement posted to its website late Friday night, the ministry reiterated the terms of the latest resolution, writing that UN member states would not export more than 500,000 barrels of refined petroleum products to the North in the final three months of 2017, and 2 million annually starting next year.

"Chinese government authorities will issue a notice based on the export situation when approaching the upper limit, and from that date implement a prohibition on exports of refined oil products to North Korea for the year," it said.

It added that China has issued a "comprehensive ban on imported textiles" from North Korea, reiterating another clause of the new sanctions that prohibits trade in both fabric and clothing.

Experts say this move could cut off a major source of foreign currency for Pyongyang, as textiles are one of country's major exports, estimated by IHS Markit analysts to value $750 million.

Frank Hersey reports from Beijing

China supplies materials to the North, where they are made into clothing in factories using cheap labour, and often re-exported to China.